Statistical Study of Turbulence Near Piano Key Weir: A Review

Abstract

Piano Key Weirs are more efficient than the traditional Labyrinth weir and Piano Key Weirs can be an interesting solution for increasing the active storage of reservoir or for improving the safety of dam during extreme flood. This technology helps to reduce the reservoir sedimentation. It will also help in minimizing the sub-mergence effect. Flushing is vital for the preservation of long-term storage in reservoirs. However, downstream impacts such as turbidity act as a constraint in the planning and operation of sediment flushing. Physics especially about turbulence phenomena will be helpful to decide the design criteria. Turbulent mixing is an important process controlling the descent rate, water mass modification and volume transport. Under stable conditions dissipation essentially balances shear production, while turbulent transport and buoyant production are of secondary importance. Under unstable conditions, dissipation slightly exceeds the total production, and energy is also lost at a substantial rate due to upward export by the turbulence. Theoretical analysis and prediction of turbulence has been problem of fluid dynamics due to random or chaotic nature of turbulence phenomena. Because of this unpredictability, it has been usual to work with the time averaged forms of the governing equations, which inevitably results in terms involving higher order correlations of fluctuating quantities of flow variables. Turbulence is a very complex phenomenon so near PKW occurrence need extensive laboratory experiment and analysis of these results through some statistics will be reliable. This paper deals with issues, gaps and scope of statistical turbulence study near PKW.